[34-longterm 146/179] dm mpath: fix potential NULL pointer in feature arg processing

[Paul Gortmaker]

From: Mike Snitzer <snitzer@xxxxxxxxxx>

                   -------------------
    This is a commit scheduled for the next v2.6.34 longterm release.
    http://git.kernel.org/?p=linux/kernel/git/paulg/longterm-queue-2.6.34.git
    If you see a problem with using this for longterm, please comment.
                   -------------------

commit 286f367dad40beb3234a18c17391d03ba939a7f3 upstream.

Avoid dereferencing a NULL pointer if the number of feature arguments
supplied is fewer than indicated.

Signed-off-by: Mike Snitzer <snitzer@xxxxxxxxxx>
Signed-off-by: Alasdair G Kergon <agk@xxxxxxxxxx>
Signed-off-by: Paul Gortmaker <paul.gortmaker@xxxxxxxxxxxxx>
---
 drivers/md/dm-mpath.c |    5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c
index ed1d0c2..78090eb 100644
--- a/drivers/md/dm-mpath.c
+++ b/drivers/md/dm-mpath.c
@@ -793,6 +793,11 @@ static int parse_features(struct arg_set *as, struct multipath *m)
 	if (!argc)
 		return 0;
 
+	if (argc > as->argc) {
+		ti->error = "not enough arguments for features";
+		return -EINVAL;
+	}
+
 	do {
 		param_name = shift(as);
 		argc--;
-- 
1.7.9.6

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